Patent GB-1237737-A (GB)
Title: Control system for a double burner oven
Inventor: GENBAUFFE FRANCIS SIMON
IPC: F23N5/08
Filed: 1968-09-25
Abstract: 1,237,737. Controlling burners. ROBERTSHAW CONTROLS CO. 25 Sept., 1968 [26 Sept., 1967], No. 45601/68. Heading F4T. In a control system for a bake burner 21 and a broil burner 22 supplied with fuel from a manifold 23 through a control device 24 and a conduit 29 containing a diverter valve 40, the control device 24 either causes the diverter valve 40 to direct fuel to the bake burner 21 or to the broil burner 22. A safety valve 34 is situated in the conduit 29 between the control device 24 and the diverter valve 40 and is opened when a flame detector 41 senses an enlarged flame at a bake pilot 42 which has a continuously burning small standby flame which is insufficient to activate the detector 41. A broil pilot 61 is only ignited when a broiling operation is selected. The temperature produced by the burners 21, 22 is sensed by a bulb 85 which controls the control device 24. The diverter valve 40 has a pair of outlets 43, 44 connected to the broil burner 22 and the bake burner 21, and controlled by a valve member 51 spring biased to open the outlet 44, and a valve member 53 biased to close the outlet 43. A power element 57 having a movable wall 56 connected to the valve member 51 is connected to a bulb 59 which senses a flame at the broil pilot 61 when a broiling operation is selected and pivots the valve member 51 to close the outlet 44 and engage the valve member 53 to cause pivoting thereof to open the outlet 43. In operation, when the selector knob 25 of the control device 24 is set for baking additional fuel is supplied to the bake pilot 42 which thus activates the detector 41 to open the safety valve 34 so that fuel passes to the bake burner through the diverter valve 40. When a predetermined temperature is reached the bulb 85 causes the control device 24 to terminate the additional fuel supply to the bake pilot 42, thus closing the safety valve 34. When the knob 25 is set for broiling the additional fuel is again applied to the bake pilot 42 thus opening the safety valve 34, and fuel is also supplied to the broil pilot 61 through a conduit 62 containing a pressure switch 63. The switch 63 closes to energize an igniter coil 80 to ignite the broil pilot 61 which then activates the detector 59 to switch over the diverter valve 40. The diverter valve 40 is then switched over and trips the plunger 86 of a switch 74 to de-energize the coil 80. When the bulb 85 senses a predetermined temperature, the fuel supply to the bake pilot 42 is reduced and the safety valve 34 closes, the broil pilot 61 still being supplied with fuel. During high temperature operation the broil burner 22 is throttled as hereinafter described. The control device 24 (see Fig. 2) has a casing 26 with an inlet 27 and an outlet 28 between which is a disc valve 87 (Figs. 3, 4, 5 and 6A, not shown). Fuel from the inlet 27 is supplied to the bake pilot 42 through a passage 117 situated upstream of the disc valve 87, a filter chamber 118, and a passage 119 which opens into a bore 111. An adjusting key 112 is rotatably received in the bore 111 and has bores 113, 114, 115, which connect the passage 119 to a passage 116 leading to the bake pilot 42. When the knob 25 is set for baking or broiling, fuel passes from the valve 87 through a passage 88 to a chamber 89 which is separated from a chamber 91 by a valve 92 controlled by a valve member 94 and thence through a passage 110 to the bore 111 and the bake pilot 42. A fulcrum pin 96 is axially movable by the knob 25 and carries a spring-urged lever 99 one end 107 of which opens the valve 92. The other end 100 of the lever 99 is engaged by a movable wall 101 of an expansible member 102 connected to the bulb 85 and carrying a valve member 105 for closing a valve seat 106 between disc valve 87 and the outlet 28. When the device 24 is set for hightemperature broiling the fulcrum pin 96 moves the valve member 94 completely away from the valve seat 92 and when the bulb 85 reaches a predetermined temperature the lever 99 is pivoted to throttle the valve 105, 106 before closure of valve 92, 94 so that the bake pilot 42 does not go out. In other embodiments (Figs. 6-18, not shown), the ignition coil 80 is replaced by a broil pilot similar to the bake pilot 42, the broil pilot is ignited by means of a flash tube leading to a continuously burning pilot, or the bake pilot is ignited by an ignition coil. The safety valve 34 can be disposed between the diverter valve 40 and the bake burner 21, utilizing either flash tube or electrical ignition for the broil burner.